GPS Running Watches / Garmin Instinct 3 Solar (45mm) vs Amazfit T-Rex 3 Pro (48mm)
Garmin Instinct 3 Solar (45mm) vs Amazfit T-Rex 3 Pro (48mm)
Amazfit T-Rex 3 Pro (48mm)
Flagship materials, maps and 38 h of dual-band GPS for $399 — with clumsy map downloads.
Wins overall by 0.4 points
Quick Verdict
A 0.4-point gap makes the Amazfit T-Rex 3 Pro (48mm) the straightforward choice here. Flagship materials, maps and 38 h of dual-band GPS for $399 — with clumsy map downloads.
The Garmin Instinct 3 Solar (45mm) and Amazfit T-Rex 3 Pro (48mm) are both current-generation GPS Running Watch models, and they're priced almost identically ($399.99 vs $399.99). On Navigation & Maps, the Amazfit T-Rex 3 Pro (48mm) leads (7.2 vs 2.8/10) — real routable offline topographic maps versus a breadcrumb line, plus how painful it is to get maps onto the watch.. On Display, the Amazfit T-Rex 3 Pro (48mm) leads (9.5 vs 6.4/10) — brightness, resolution and daylight readability, weighing AMOLED sharpness against MIP's always-on-for-free behaviour.. On Value, the Amazfit T-Rex 3 Pro (48mm) leads (9.0 vs 7.0/10) — what the watch delivers per dollar against everything else in the comparison at the moment of purchase.. Overall, the Amazfit T-Rex 3 Pro (48mm) scores 7.6/10 across our 8 scoring categories versus 7.2/10 for the Garmin Instinct 3 Solar (45mm). Below, we break down the full spec sheet, category-by-category scores, and exactly who should buy which one.
Side-by-Side Comparison
| Spec | Garmin Instinct 3 Solar (45mm) | Amazfit T-Rex 3 Pro (48mm) |
|---|---|---|
| Price | $399.99 | $399.99 |
| Release Year | 2025 | 2025 |
| Display | Monochrome 176x176 transflective MIP, always-on by design, no touchscreen — readable in direct sun and costs almost nothing to leave on | 1.5-in AMOLED, up to 3,000 nits, sapphire crystal lens, optional always-on |
| Smartwatch Battery ( days) | 28✓ | 25 |
| Always-On Display Cost | There is no always-on penalty: MIP is always on. With 3 h/day at 50,000 lux the solar lens makes smartwatch mode effectively unlimited and stretches multiband GPS from 24 h to about 60 h. | Amazfit's 25-day figure is typical use; heavy use is rated 10 days and one reviewer measured about 18 days alongside 14 h of accurate GPS. Amazfit does not publish a separate always-on display figure. |
| Battery, Single-Band GPS ( h) | Sources conflict: 40 h (the5krunner spec sheet, 45 mm, no solar) vs 50 h (garminrumors spec wiki, lower bound of its 45/50 mm range) | 85 |
| Battery, Multiband GPS ( h) | 24 | 38✓ |
| GNSS Bands | Multi-band dual-frequency L1+L5 (GPS, GLONASS, Galileo, BeiDou, QZSS) with SatIQ — DC Rainmaker confirms every Instinct 3 got multiband | Dual-band (L1+L5) circularly-polarised GNSS. The 85 h headline is the power-saving GPS mode; the accurate dual-band mode is 37-38 h on the 48 mm and about 29 h on the 44 mm. |
| Onboard Maps | None. No offline maps and no route storage to speak of — DC Rainmaker called shipping a $400-plus outdoor watch without maps 'pretty hard to swallow'. | Free offline contour maps with turn-by-turn, POI search, round-trip routing and auto-rerouting — but you must select and download each map region inside the Zepp phone app and transfer it across. Android Police called the process 'messy and time-consuming' with vague instructions. |
| Music Storage | None. No music storage, no streaming, no Wi-Fi — phone music control only. | Onboard storage for sideloaded MP3 files played to Bluetooth headphones. No Spotify and no streaming services. |
| Training Platform & Subscription | Garmin Connect is free and every core training metric — Training Readiness, Training Load, Training Status, HRV Status, Body Battery, recovery time — is Firstbeat-derived and free on the watch (Garmin bought Firstbeat in 2020). Connect+ is $6.99/mo or $69.99/yr and adds only AI wellness prompts, 3D maps, Trails+ routing, extra badges and nutrition logging — nothing a training plan depends on. | The Zepp app and core training/recovery metrics are free. Zepp Aura, the AI sleep and coaching layer, is a paid subscription; the training data itself is not gated behind it. |
| External Sensor Support | ANT+ and Bluetooth chest straps, pods and power meters | Bluetooth only — no ANT+. BLE chest straps and Stryd pods pair through Zepp OS. |
| Data Export | Full .FIT file access over USB/MTP plus free automatic sync to Strava, TrainingPeaks, Runalyze, intervals.icu and others through Garmin Connect. | Free sync to Strava, adidas Running, Apple Health and Google Health Connect, plus a TrainingPeaks Zepp OS app; .FIT export via the Zepp app |
| Warranty | 12 months | 12 months |
| Colors | Black | Black |
Category Scores
GPS Accuracy
The Garmin Instinct 3 Solar (45mm) leads clearly here, 8.6 against 7.8 — a 0.8-point margin on trace quality in cities and under tree cover — multiband L1+L5 hardware plus what independent testers measured in the real world.. If that is what you are buying for, the Amazfit T-Rex 3 Pro (48mm) does not close the gap elsewhere.
Battery Honesty
The Garmin Instinct 3 Solar (45mm) leads clearly here, 9.2 against 7.6 — a 1.6-point margin on how much of the headline battery claim survives the mode you would actually train in: all-systems plus multiband, always-on display, music playing. The number on the box is almost always the slowest, least accurate mode.. If that is what you are buying for, the Amazfit T-Rex 3 Pro (48mm) does not close the gap elsewhere.
Training & Recovery
The Garmin Instinct 3 Solar (45mm) leads clearly here, 7.8 against 6.8 — a 1.0-point margin on depth of load, readiness and recovery analysis, and how much of it is free rather than gated behind a subscription or an extra chest strap.. If that is what you are buying for, the Amazfit T-Rex 3 Pro (48mm) does not close the gap elsewhere.
Heart Rate
The Garmin Instinct 3 Solar (45mm) is marginally ahead, 7.2 to 6.8. A gap this small rarely decides a purchase on its own, though it counts if optical wrist accuracy during intervals and burst efforts, and whether the watch pairs with ANT+ and/or Bluetooth chest straps as a fix. is your priority.
Display
The Amazfit T-Rex 3 Pro (48mm) leads clearly here, 9.5 against 6.4 — a 3.1-point margin on brightness, resolution and daylight readability, weighing AMOLED sharpness against MIP's always-on-for-free behaviour.. If that is what you are buying for, the Garmin Instinct 3 Solar (45mm) does not close the gap elsewhere.
Build & Comfort
The Garmin Instinct 3 Solar (45mm) leads clearly here, 8.2 against 6.4 — a 1.8-point margin on case materials, lens (sapphire vs glass), weight on the wrist and durability ratings.. If that is what you are buying for, the Amazfit T-Rex 3 Pro (48mm) does not close the gap elsewhere.
Value
The Amazfit T-Rex 3 Pro (48mm) leads clearly here, 9.0 against 7.0 — a 2.0-point margin on what the watch delivers per dollar against everything else in the comparison at the moment of purchase.. If that is what you are buying for, the Garmin Instinct 3 Solar (45mm) does not close the gap elsewhere.
Best For
Choose the Garmin Instinct 3 Solar (45mm) if…
- • Build & Comfort matters most to you — the Garmin Instinct 3 Solar (45mm) scores 8.2/10 here (case materials, lens (sapphire vs glass), weight on the wrist and durability ratings.).
- • Battery Honesty matters most to you — the Garmin Instinct 3 Solar (45mm) scores 9.2/10 here (how much of the headline battery claim survives the mode you would actually train in: all-systems plus multiband, always-on display, music playing. The number on the box is almost always the slowest, least accurate mode.).
Choose the Amazfit T-Rex 3 Pro (48mm) if…
- • Navigation & Maps matters most to you — the Amazfit T-Rex 3 Pro (48mm) scores 7.2/10 here (real routable offline topographic maps versus a breadcrumb line, plus how painful it is to get maps onto the watch.).
- • Display matters most to you — the Amazfit T-Rex 3 Pro (48mm) scores 9.5/10 here (brightness, resolution and daylight readability, weighing AMOLED sharpness against MIP's always-on-for-free behaviour.).
- • Value matters most to you — the Amazfit T-Rex 3 Pro (48mm) scores 9.0/10 here (what the watch delivers per dollar against everything else in the comparison at the moment of purchase.).
Pros & Cons
Garmin Instinct 3 Solar (45mm)
Pros
- +MIP plus solar is the one combination here where the headline battery figure is close to what you actually get
- +Multi-band L1+L5 GNSS at $399.99, in a 10 ATM, MIL-STD-810 tested case
- +Solar can push smartwatch mode to effectively unlimited and multiband GPS from 24 h to about 60 h
- +No always-on display penalty at all — the screen is transflective and permanently visible
Cons
- −No offline maps and no music storage, on a watch that costs as much as an Amazfit T-Rex 3 Pro that has both
- −Storage is the reason: sources conflict badly — the garminrumors wiki says 32 GB while DC Rainmaker and Tom's Guide report roughly 120-128 MB on Solar models, too small even to hold a firmware update alongside courses
- −Multiband drops runtime to 24 h without sun — a quarter of the 100 h Max Battery GPS headline
- −Older Elevate Gen 4 optical HR sensor, not the Gen 5 in cheaper Garmins
- −Monochrome 176x176 MIP screen looks a decade old next to every AMOLED rival, and there is no touchscreen
Amazfit T-Rex 3 Pro (48mm)
Pros
- +38 h of dual-band GPS and 25 days of typical use for $399.99 — Garmin charges $1,199.99 for 30 h of multiband
- +A 3,000-nit AMOLED behind sapphire with a titanium-alloy bezel at half the price of rivals with those materials
- +Free offline contour maps with genuine auto-rerouting, which even the $749.99 Forerunner 970 does not beat on price
- +10 ATM plus EN13319 freediving certification to 45 m, unusual at any price
Cons
- −Maps must be picked and downloaded region-by-region in the Zepp phone app then transferred — reviewers describe the process as messy and poorly documented
- −The 85 h battery headline is the power-saving GPS mode; the dual-band mode you would actually race on is 38 h
- −No ANT+ and no Spotify or any streaming service — sideloaded MP3 only
- −Zepp's software ecosystem and analytics are a clear step behind Garmin and COROS, and the app is cluttered
- −48 mm and chunky; reviewers found it too bulky for 24-hour wear
Shop by Need
FAQs
Is the Garmin Instinct 3 Solar (45mm) or Amazfit T-Rex 3 Pro (48mm) better overall?+
Based on our 8-category scoring, the Amazfit T-Rex 3 Pro (48mm) comes out ahead overall. See the full breakdown in the scores section above — the right pick still depends on which categories matter most for your use case.
Which is better for Navigation & Maps, the Garmin Instinct 3 Solar (45mm) or the Amazfit T-Rex 3 Pro (48mm)?+
The Amazfit T-Rex 3 Pro (48mm) scores higher on Navigation & Maps (7.2/10 vs 2.8/10) — real routable offline topographic maps versus a breadcrumb line, plus how painful it is to get maps onto the watch..
Which is better for Display, the Garmin Instinct 3 Solar (45mm) or the Amazfit T-Rex 3 Pro (48mm)?+
The Amazfit T-Rex 3 Pro (48mm) scores higher on Display (9.5/10 vs 6.4/10) — brightness, resolution and daylight readability, weighing AMOLED sharpness against MIP's always-on-for-free behaviour..
Which is better for Value, the Garmin Instinct 3 Solar (45mm) or the Amazfit T-Rex 3 Pro (48mm)?+
The Amazfit T-Rex 3 Pro (48mm) scores higher on Value (9.0/10 vs 7.0/10) — what the watch delivers per dollar against everything else in the comparison at the moment of purchase..
Which is better for Build & Comfort, the Garmin Instinct 3 Solar (45mm) or the Amazfit T-Rex 3 Pro (48mm)?+
The Garmin Instinct 3 Solar (45mm) scores higher on Build & Comfort (8.2/10 vs 6.4/10) — case materials, lens (sapphire vs glass), weight on the wrist and durability ratings..
Is the Garmin Instinct 3 Solar (45mm) worth the price difference over the Amazfit T-Rex 3 Pro (48mm)?+
They're priced the same ($399.99), so the decision comes down to which specific features and scores matter more to you rather than budget.
What's the warranty on the Garmin Instinct 3 Solar (45mm) vs the Amazfit T-Rex 3 Pro (48mm)?+
The Garmin Instinct 3 Solar (45mm) ships with a 12-month warranty; the Amazfit T-Rex 3 Pro (48mm) ships with a 12-month warranty. Always confirm current terms on the manufacturer's site before buying.
Should I wait for the next model instead of buying either of these?+
If either model is more than two years old, a successor may be close — check the "Latest Model" link on each product page. Otherwise, both are current, well-supported options and there's no strong reason to wait.
Cheaper Option
Garmin Forerunner 170 (43mm) — $299.99
Premium Option
COROS APEX 4 (42mm) — $429.00
Specifications and prices for both products last verified . Scores are calculated from published specifications — see how we compare products.